(a) Field of the Invention
The present invention is related to an open end wrench, and more particularly, to an improved structure of an adjustable opening size to allow inching, fixed opening, automatic release of work piece and easy operation.
(b) Description of the Prior Art
Whereas as illustrated in FIG. 1 of the accompanying drawings, a conventional open end wrench has a fixed size of its opening, meaning, a set of wrenches in different sizes must be prepared depending on the size of the individual work piece. However, the drawbacks are that it is not convenient to carry along the set of wrenches and that frequent change among wrenches of various sizes is required. Another wrench as shown in FIG. 2 allows reciprocal movement of a movable jaw by turning a thumbscrew to form a clamping space with a fixed jaw to clamp on a work piece. However, it prevents fast and convenient operation since the operator has use his fingers to operate a thumbscrew either for clamping or releasing the work piece. Furthermore, the peripheral of the thumbscrew is made slightly higher than the surface of the wrench for easier contact by fingers of the operator; but the thumbscrew is at the same time vulnerable to be contacted by objects close to it to cause the movable jaw to open up, thus to lose the clamping of the work piece. Consequently, it becomes extremely inconvenient since frequent adjustment of the thumbscrew is required to control the clamping space.
The primary purpose of the present invention is to provide an improved structure of an open end wrench comprised of a fixed jaw and a movable jaw that allows laterally reciprocal movement. While clamping a work piece, the movable jaw is pushed inwardly and then restricted by a locking gear to fix a clamping space; while releasing the work piece, the locking gear is dialed to allow the movable jaw to automatically clear away from the work piece.
Another purpose of the present invention is to provide an improved structure of an open end wrench that is compact, allowing easy manufacturing and assembly and excellent control of its precision.
To achieve the purposes, the present invention is essentially comprised of a fixed jaw and a movable jaw with both sharing a constant relation of relatively lateral slide against each other and a fluted surface is provided at the lower edge of the movable jaw; a spring provided between the fixed jaw and the movable jaw having one end fixed to the fixed jaw and the other end fixed to the movable jaw to define a clamping space under normal status by the clamping parts respectively from the movable and the fixed jaws due to the tension provided by the spring; and a locking gear allowing reciprocal and flexible circulation made in V-shape and having one end provided with a ratchet to engage the fluted surface of the movable jaw and the other end provided with a dialer to control the ratchet to clear away from the fluted surface.